... : 1.certification:ISO9001,CCC,CE,Solar Keymark 2.solar water heater:evacuated tube 3.pressure:non-press Solar new energy: material:1.volume of storage ... pressure:0.4bar,3.dust ring gasket :ABS4.evacuated tube:three-target tube,high boron and silicon,content 3.3,structure,gradual ... .Suitable for campong area,holiday residences.5.water introduced into vacuum tube6.long service life,can be used as long as ...